Cosmetic formulation comprising dihydroxyacetone

ABSTRACT

The invention relates to cosmetic formulations containing dihydroxy-acetone and a topical support in addition to one or several compounds selected from the compounds of formulae (Ia) and (Ib), the physiologically acceptable salts of compounds of formulae (Ia) and (Ib), and the stereoisomeric forms of formulae (Ia) and (Ib), wherein R 1 , R 2 , R 3 , R 4  and n have the meanings cited in Claim  1 . The cosmetic formulations are characterized in that the UV-A protective effect of dihydroxyacetone is increased.

The invention relates to cosmetic formulations based ondihydroxyacetone. These formulations can be used, for example, forself-tanning.

A certain degree of tanning of the skin is regarded in modern society asattractive and as an expression of vigour and sportiness. Tanning ofthis type can be achieved, for example, by means of sunbathing orthrough the use of self-tanning agents.

In addition to the desired action of the sun, tanning, a number ofundesired side effects, such as sunburn or premature skin ageing andwrinkling, also occur on exposure of the human skin to the sun. As isknown, the most dangerous part of sunlight is formed by ultraviolet rayshaving a wave-length of less than 400 nm. Part of this UV radiation,UV-A radiation in the range from 320 to 400 nm, tans the skin, but alsocauses it to age and promotes the initiation of erythematic reactions.It may also increase the erythematic reaction in certain people or eveninitiate phototoxic or photoallergic and irritative reactions.

However, the tanning achieved through exposure of the human skin to thesun also forms a certain degree of natural protection of the skinagainst UV rays, i.e. people who already have tanned skin throughexposure to the sun are better protected, for example, against theharmful effects of UV-A radiation than are people whose skin has not yetbeen tanned by exposure to the sun.

It is known, for example, that compounds containing a ketol group

such as, for example, hydroxymethyl ketones, for example methylglyoxaland in particular dihydroxyacetone, exert a self-tanning action on thehuman skin and are therefore suitable for use in self-tanning agents.The self-tanning effect of these compounds is essentially based on aMaillard reaction between the ketol group of these compounds and theamino acids of the skin.

There are, for example, also indications that the tanning of the skincaused by dihydroxyacetone likewise provides protection against UV-Arays [K. A. Follett et al., Dermatologica 175 (1987) 58-63; J. A.Johnson et al., Dermatologica 175 (1987) 53-57; R. A. Wakeel et al.,British Journal of Dermatology 1 (1992) 94]. However, this protection iscomparatively weak. It is generally known that the protection againstUV-A rays achieved through tanning of the skin achieved with the aid ofdihydroxyacetone is not as pronounced as the protection effected by suntanning. The user of self-tanning compositions based on dihydroxyacetoneshould accordingly make particularly sure that their skin is protectedagainst UV and in particular against UV-A rays if they are exposed tothese rays.

The object of the present invention was therefore to provide cosmeticformulations based on dihydroxyacetone which avoid the disadvantages ofthe prior art and in particular result in improved UV-A protection whenapplied to the skin.

Surprisingly, it has now been found that this object is achieved throughthe use of one or more compounds selected from the compounds of theformulae Ia and Ib

physiologically tolerated salts of the compounds of the formulae Ia andIb and stereoisomeric forms of the compounds of the formulae Ia and Ib,where

-   R¹ is H or alkyl,-   R² is H, COOH, COO-alkyl or CO—NH—R⁵,-   R³ and R⁴ are each, independently of one another, H or OH,-   n is1, 2 or 3,-   alkyl is an alkyl radical having from 1 to 4 carbon atoms, and-   R⁵ is H, alkyl, an amino acid radical, a dipeptide radical or a    tripeptide radical,    in cosmetic formulations comprising dihydroxyacetone and a topical    vehicle.

The invention thus relates to cosmetic formulations comprisingdihydroxy-acetone and a topical vehicle, characterised in that thecomposition additionally comprises one or more compounds selected fromthe compounds of the formulae Ia and Ib

physiologically tolerated salts of the compounds of the formulae Ia andIb and stereoisomeric forms of the compounds of the formulae Ia and Ib,where

-   R¹ is H or alkyl,-   R² is H, COOH, COO-alkyl or CO—NH—R⁵,-   R³ and R⁴ are each, independently of one another, H or OH,-   n is 1, 2 or 3,-   alkyl is an alkyl radical having from 1 to 4 carbon atoms, and-   R⁵ is H, alkyl, an amino acid radical, a dipeptide radical or a    tripeptide radical.

It is also surprising that the formulations comprising dihydroxyacetoneand one or more compounds selected from the compounds of the formulae Iaand Ib, physiologically tolerated salts of the compounds of the formulaeIa and Ib and stereoisomeric forms of the compounds of the formulae Iaand Ib are stable since it is generally known that formulationscomprising dihydroxyacetone and nitrogen-containing compounds, such as,for example, amino acids, have stability problems. This is attributable,for example, to the degradation of dihydroxyacetone in the presence ofamino acids, which is even accelerated at elevated temperature. However,it has been found that dihydroxyacetone and one or more compoundsselected from the compounds of the formulae Ia and Ib, physiologicallytolerated salts of the compounds of the formulae Ia and Ib andstereoisomeric forms of the compounds of the formulae Ia and Ib can beincorporated into cosmetic formulations without stability problemsarising or particular precautions having to be taken with respect to thestability of the resultant cosmetic formulation. This also applies, forexample, within a certain latitude for an elevated storage temperatureof the cosmetic formulations according to the invention.

For the purposes of the present invention, all compounds above and belowselected from the compounds of the formulae Ia and Ib, physiologicallytolerated salts of the compounds of the formulae Ia and Ib andstereoisomeric forms of the compounds of the formulae Ia and Ib arereferred to as “ectoin or ectoin derivatives”.

Ectoin and ectoin derivatives are low-molecular-weight, cyclic aminoacid derivatives which can be isolated from various halophilicmicroorganisms or prepared synthetically. Both ectoin and hydroxyectoinhave the advantage of not reacting with the cell metabolism.

The compounds selected from the compounds of the formulae Ia and Ib,physiologically tolerated salts of the compounds of the formulae Ia andIb and stereoisomeric forms of the compounds of the formulae Ia and Ibmay be present in the cosmetic formulations according to the inventionin the form of optical isomers, diastereomers, racemates, zwitterions,cations or a mixture thereof. Of the compounds selected from thecompounds of the formulae Ia and Ib, physiologically tolerated salts ofthe compounds of the formulae Ia and Ib and stereoisomeric forms of thecompounds of the formulae Ia and Ib, preference is given to thosecompounds in which R¹ is H or CH₃, R² is H or COOH, R³ and R⁴ are each,independently of one another, H or OH, and n is 2. Of the compoundsselected from the compounds of the formulae Ia and Ib, physiologicallytolerated salts of the compounds of the formulae Ia and Ib andstereoisomeric forms of the compounds of the formulae Ia and Ib,particular preference is given to the compounds(S)-1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid (ectoin) and(S,S)-1,4,5,6-tetrahydro-5-hydroxy-2-methyl-4-pyrimidine-carboxylic acid(hydroxyectoin).

The amino acid radicals mentioned in the radical R⁵ of the compounds ofthe formulae Ia and Ib are derived from the corresponding amino acids.The term “amino acids” is taken to mean the stereoisomeric forms, forexample D and L forms, of the following compounds: alanine, β-alanine,arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid,glycine, histidine, isoleucine, leucine, lysine, methionine,phenylalanine, serine, threonine, tryptophan, tyrosine, valine,γ-aminobutyrate, Nε-acetyllysine, Nδ-acetylornithine,Nγ-acetyldiaminobutyrate and Nα-acetyldiaminobutyrate. L-amino acids arepreferred. The radicals of the following amino acids are preferred:alanine, β-alanine, asparagine, aspartic acid, glutamine, glutamic acid,glycine, serine, threonine, valine, γ-aminobutyrate, Nε-acetyllysine,Nδ-acetylornithine, Nγ-acetyldiaminobutyrate andNα-acetyldiaminobutyrate.

The di- and tripeptide radicals mentioned in the radical R⁵ of thecompounds of the formulae Ia and Ib are acid amides from the point ofview of their chemical nature and decompose on hydrolysis to give 2 or 3amino acids. The amino acids in the di- and tripeptide radicals arebonded to one another by amide bonds. Preferred di- and tripeptideradicals are built up from the preferred amino acids.

The alkyl groups mentioned in the radicals R¹, R² and R⁵ of thecompounds of the formulae Ia and Ib include the methyl group CH₃, theethyl group C₂H₅, the propyl groups CH₂CH₂CH₃ and CH(CH₃)₂ and the butylgroups CH₂CH₂CH₂CH₃, H₃CCHCH₂CH₃, CH₂CH(CH₃)₂ and C(CH₃)₃. The preferredalkyl group is the methyl group.

Preferred physiologically tolerated salts of the compounds of theformulae Ia and Ib are, for example, alkali metal, alkaline earth metalor ammonium salts, such as Na, K, Mg or Ca salts, and salts derived fromthe organic bases triethylamine or tris(2-hydroxyethyl)amine. Furtherpreferred physiologically tolerated salts of the compounds of theformulae Ia and Ib are formed by reaction with inorganic acids, such ashydrochloric acid, sulfuric acid and phosphoric acid, or with organiccarboxylic or sulfonic acids, such as acetic acid, citric acid, benzoicacid, maleic acid, fumaric acid, tartaric acid and p-toluenesulfonicacid.

Compounds of the formulae Ia and Ib in which basic and acidic groups,such as carboxyl or amino groups, are present in the same number forminternal salts.

The preparation of the compounds of the formulae Ia and Ib is describedin the literature (DE 43 42 560).(S)-1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid and(S,S)-1,4,5,6-tetrahydro-5-hydroxy-2-methyl-4-pyrimidinecarboxylic acidcan also be obtained microbiologically (Severin et al., J. Gen. Microb.138 (1992) 1629-1638).

The use of compounds selected from the compounds of the formulae Ia andIb for cosmetic and also pharmaceutical purposes is already known.

For example, WO 94/15923 describes that(S)-1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid or(S,S)-1,4,5,6-tetrahydro-5-hydroxy-2-methyl-4-pyrimidinecarboxylic acidcan be used for the preparation of a cosmetic preparation or of amedicament, for example for the treatment of skin diseases.

Furthermore, DE 43 42 560 describes the use of ectoin and ectoinderivatives as moisturisers in cosmetic products. These products aresuitable, for example, for the care of aged, dry or irritated skin.

DE 199 33 466 furthermore describes that ectoin and derivatives, such ashydroxyectoin, can be employed as antioxidants and free-radicalscavengers in cosmetic and dermatological preparations. The preparationscan be used for the treatment and/or prophylaxis of skin ageing causedby oxidative stress and of inflammatory reactions.

Further applications of ectoin and ectoin derivatives in cosmeticformulations are described, for example, in WO 00/07558, WO 00/07559 andWO 00/07560, such as, for example, the care and prophylaxis of dryand/or flaky skin, protection of human skin against dryness and/or highsalt concentrations, protection of cells, proteins and/or biomembranesof human skin, protection of the microflora of human skin, stabilisationof the skin barrier, and protection and stabilisation of the nucleicacids of human skin cells.

However, it was hitherto not known that the compounds selected from thecompounds of the formulae Ia and Ib can advantageously be used incosmetic formulations comprising dihydroxyacetone and that they cansignificantly augment, for example, the UV-A-protective action ofdihydroxyacetone.

The present invention therefore also relates to the use of one or morecompounds selected from the compounds of the formulae Ia and Ib foraugmenting the UV-A-protective action of dihydroxyacetone, in particularin cosmetic formulations.

However, the cosmetic formulations according to the invention are alsosuitable, for example, for the applications of ectoin and derivativesthereof which are mentioned above and those which are known from theprior art. The present application therefore likewise relates to the useof the cosmetic formulations according to the invention for theseapplications.

Examples of the cosmetic formulations according to the invention are,inter alia, self-tanning compositions, products for day care andlight-protection formulations. In a preferred embodiment, the cosmeticcompositions according to the invention are used as self-tanning agents.

The proportion of dihydroxyacetone in the cosmetic formulation accordingto the invention is preferably from 0.1 to 15% by weight, particularlypreferably from 0.1 to 10% by weight and especially preferably from 1 to7% by weight, based on the formulation as a whole. The proportion ofdihydroxyacetone in the cosmetic formulation according to the inventionis very especially preferably from 2 to 5% by weight, based on theformulation as a whole.

The proportion of compounds selected from the compounds of the formulaeIa and Ib, physiologically tolerated salts of the compounds of theformulae Ia and Ib and stereoisomeric forms of the compounds of theformulae Ia and Ib in the cosmetic formulation according to theinvention is preferably from 0.001 to 50% by weight, particularlypreferably from 0.01 to 10% by weight and especially preferably from 0.1to 10% by weight, based on the cosmetic formulation as a whole. Theproportion of the said compounds in the cosmetic formulation accordingto the invention is very especially preferably from 0.1 to 5% by weight,based on the formulation as a whole.

Besides dihydroxyacetone and the compounds of the formula I, thecosmetic formulations according to the invention may also comprisefurther cosmetic active ingredients.

The cosmetic formulations according to the invention may comprise one ormore antioxidants. The cosmetic formulations according to the inventionmay comprise all common antioxidants. In this connection, there are manyproven substances known from the specialist literature which can be usedas antioxidants, for example flavonoids, coumaranones, amino acids (forexample glycine, histidine, tyrosine, tryptophan) and derivativesthereof, imidazoles (for example urocanic acid) and derivatives thereof,peptides, such as D,L-camosine, D-carnosine, L-carnosine and derivativesthereof (for example anserine), carotinoids, carotenes (for exampleα-carotene, β-carotene, lycopene) and derivatives thereof, chlorogenicacid and derivatives thereof, lipoic acid and derivatives thereof (forexample dihydrolipoic acid), aurothioglucose, propylthiouracil and otherthiols (for example thioredoxin, glutathione, cysteine, cystine,cystamine and the glycosyl, N-acetyl, methyl, ethyl, propyl, amyl, butyland lauryl, palmitoyl, oleyl, γ-linoleyl, cholesteryl and glycerylesters thereof) and salts thereof, dilauryl thiodipropionate, distearylthiodipropionate, thiodipropionic acid and derivatives thereof (esters,ethers, peptides, lipids, nucleotides, nucleosides and salts), andsulfoximine compounds (for example buthionine sulfoximines, homocysteinesulfoximine, buthionine sulfones, penta-, hexa- and hepta-thioninesulfoximine) in very low tolerated doses (for example pmol to μmol/kg),and also (metal) chelating agents (for example α-hydroxy fatty acids,palmitic acid, phytic acid, lactoferrin), α-hydroxy acids (for examplecitric acid, lactic acid, malic acid), humic acid, bile acid, bileextracts, bilirubin, biliverdin, EDTA, EGTA and derivatives thereof,unsaturated fatty acids and derivatives thereof, vitamin C andderivatives (for example ascorbyl palmitate, magnesium ascorbylphosphate, ascorbyl acetate), tocopherols and derivatives (for examplevitamin E acetate), vitamin A and derivatives (for example vitamin Apalmitate), and coniferyl benzoate of benzoin resin, rutinic acid andderivatives thereof, α-glycosyl rutin, ferulic acid,furfurylideneglucitol, carnosine, butylhydroxytoluene,butylhydroxy-anisole, nordihydroguaiaretic acid,trihydroxybutyrophenone, quercetin, uric acid and derivatives thereof,mannose and derivatives thereof, zinc and derivatives thereof (forexample ZnO, ZnSO₄), selenium and derivatives thereof (for exampleselenomethionine), stilbenes and derivatives thereof (for examplestilbene oxide, trans-stilbene oxide), metal bisulfite salts, sulfitesalts or hydrogensulfite salts.

Mixtures of antioxidants are likewise suitable for use in the cosmeticformulations according to the invention. Known and commercial mixturesare, for example, mixtures comprising, as active ingredients, lecithin,L-(+)-ascorbyl palmitate and citric acid (for example Oxynex® AP),natural tocopherols, L-(+)-ascorbyl palmitate, L-(+)-ascorbic acid andcitric acid (for example Oxynex® K LIQUID), tocopherol extracts fromnatural sources, L-(+)-ascorbyl palmitate, L-(+)-ascorbic acid andcitric acid (for example Oxynex® L LIQUID), DL-α-tocopherol,L-(+)-ascorbyl palmitate, citric acid and lecithin (for example Oxynex®LM) or butylhydroxytoluene (BHT), L-(+)-ascorbyl palmitate and citricacid (for example Oxynex® 2004).

A further suitable antioxidant mixture can consist, for example, of,inter alia, emblicanin A, emblicanin B, punigluconin and pendunculagin,as described, for example, in WO 00/48551 under the name CAPROS™ (forexample Emblica™).

In a preferred embodiment of the invention, the cosmetic formulationaccording to the invention comprises one or more compounds selected fromflavonoids and/or coumaranones.

Flavonoids are taken to mean the glycosides of flavonones, flavones,3-hydroxyflavones (=flavonols), aurones, isoflavones and rotenoids[Römpp Chemie Lexikon [Römpp's Lexicon of Chemistry], Volume 9, 1993].For the purposes of the present invention, however, this term is alsotaken to mean the aglycones, i.e. the sugar-free constituents, and thederivatives of the flavonoids and aglycones. For the purposes of thepresent invention, the term flavonoid is furthermore also taken to meananthocyanidine (cyanidine). For the purposes of the present invention,the term coumaranones is also taken to mean the derivatives thereof.

Preferred flavonoids are derived from flavonones, flavones,3-hydroxy-flavones, aurones and isoflavones, in particular fromflavonones, flavones, 3-hydroxyflavones and aurones.

The flavonoids are preferably selected from the following compounds:4,6,3′,4′-tetrahydroxyaurone, quercetin, rutin, isoquercetin,eriodictyol, taxifolin, luteolin, trishydroxyethylquercetin(troxequercetin), trishydroxyethylrutin (troxerutin),trishydroxyethylisoquercetin (troxeisoquercetin),trishydroxyethylluteolin (troxeluteolin), α-glycosylrutin, tilirosideand the sulfates and phosphates thereof. Of the flavonoids, particularpreference is given to rutin and troxerutin.

Of the coumaranones, preference is given to4,6,3′,4′-tetrahydroxybenzyl-3-coumaranone.

In a further preferred embodiment of the invention, in particular if thewater solubility of the flavonoids and/or coumaranones is to beincreased, a polar group, for example, in each case independently of oneanother, a sulfate or phosphate group, is bonded to one or more hydroxylgroups of these compounds. Suitable counterions are, for example, theions of the alkali or alkaline earth metals, these being selected, forexample, from sodium and potassium.

Many flavonoids and coumaranones are, for example, naturally occurring.If the cosmetic formulation according to the invention comprises suchcompounds, they may also be obtained by extraction of correspondingplants and either purified as a single substance or alternativelyintroduced into the cosmetic formulation in the form of the extract,which may, if necessary, have been refined further.

The proportion of the one or more compounds selected from flavonoids andcoumaranones in the cosmetic formulation according to the invention ispreferably from 0.001 to 5% by weight, particularly preferably from 0.01to 2% by weight, based on the formulation as a whole.

In a further preferred embodiment of the invention, the cosmeticformulation according to the invention comprises one or moreantioxidants selected from the substances citric acid, lactic acid,malic acid, EDTA, butylhydroxytoluene, ascorbic acid, ascorbylpalmitate, magnesium ascorbyl phosphate, ascorbyl acetate, tocopherol,tocopherol acetate, and metabisulfite, sulfite or hydrogensulfite saltsselected from alkali metal salts, such as sodium and potassium salts,basic metal salts and ammonium salts.

In a further preferred embodiment of the invention, the cosmeticformulation according to the invention comprises antioxidant mixtures,such as, for example, Emblica™.

The proportion of the one or more antioxidants in the cosmeticformulation according to the invention is preferably from 0.001 to 5% byweight, particularly preferably from 0.01 to 2% by weight, based on theformulation as a whole.

The cosmetic formulations according to the invention may comprise one ormore UV filters. Suitable organic UV filters are all UVA and UVB filtersknown to the person skilled in the art. For both UV ranges, there aremany proven substances which are known from the specialist literature,for example

-   benzylidenecamphor derivatives, such as    -   3-(4′-methylbenzylidene)-dl-camphor (for example Eusolex® 6300),    -   3-benzylidenecamphor (for example Mexoryl® SD),    -   polymers of N-{(2 and        4)-[(2-oxoborn-3-ylidene)methyl]benzyl}acrylamide (CAS No.        113783-61-2, for example Mexoryl® SW),    -   N,N,N-trimethyl-4-(2-oxoborn-3-ylidenemethyl)anilinium        methylsulfate (CAS No. 52793-97-2, for example Mexoryl® SK) or    -   α-(2-oxoborn-3-ylidene)toluene-4-sulfonic acid (CAS No.        56039-58-8, for example Mexoryl® SL),-   benzoyl- or dibenzoylmethanes, such as    -   1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)propane-1,3-dione (for        example Eusolex® 9020) or    -   4-isopropyidibenzoylmethane (for example Eusolex® 8020),-   benzophenones, such as    -   2-hydroxy-4-methoxybenzophenone (for example Eusolex® 4360) or    -   2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and its sodium        salt (for example Uvinul® MS-40),-   methoxycinnamic acid esters, such as    -   octyl methoxycinnamate (for example Eusolex® 2292),    -   isopentyl 4-methoxycinnamate, for example as a mixture of the        isomers (for example Neo Heliopan® E 1000),-   salicylate derivatives, such as    -   2-ethylhexyl salicylate (for example Eusolex® OS),    -   4-isopropylbenzyl salicylate (for example Megasol®) or    -   3,3,5-trimethylcyclohexyl salicylate (for example Eusolex® HMS),-   4-aminobenzoic acid and derivatives, such as    -   4-aminobenzoic acid,    -   2-ethylhexyl 4-(dimethylamino)benzoate (for example Eusolex®        6007),    -   ethoxylated ethyl 4-aminobenzoate (for example Uvinul® P25),-   benzimidazole derivatives, such as    -   2-phenylbenzimidazole-5-sulfonic acid and potassium, sodium and        triethanolamine salts thereof (for example Eusolex® 232),    -   2,2′-(1,4-phenylene)bis(1H-benzimidazole-4,6-disulfonic acid,        mono-sodium salt) (CAS No. 180 898-37-7, for example Neo        Heliopan AP),    -   2,2′-(1,4-phenylene)bis(1H-benzimidazole-5-sulfonic acid) and        potassium, sodium and triethanolamine salts thereof,-   and further substances, such as    -   2-ethylhexyl 2-cyano-3,3-diphenylacrylate (for example Eusolex®        OCR),    -   3,3′-(1,4-phenylenedimethylene)bis(7,7-dimethyl-2-oxobicyclo[2.2.        1]-hept-1-ylmethanesulfonic acid and salts thereof (for example        Mexoryl® SX),    -   2,4,6-trianilino-(p-carbo-2′-ethylhexyl-1′-oxy)-1,3,5-triazine        (for example Uvinul® T 150),    -   2-(2H-benzotriazol-2-yl)-4-methyl-6-(2-methyl-3-(1,3,3,3-tetramethyl-        1-(trimethylsilyloxy)disiloxanyl)propyl)phenol (for example        Silatrizole®),    -   2-ethylhexyl        4,4′-[(6-[4-((1,1-dimethylethyl)aminocarbonyl)phenyl-amino]-1,3,5-triazine-2,4-diyl)diimino]bis(benzoate)        (CAS NO. 154702-15-5, for example Uvasorb® HEB),    -   α-(trimethylsilyl)-ω-[trimethylsilyl)oxy]poly[oxy(dimethyl [and        about 6% of        methyl[2-[p-[2,2-bis(ethoxycarbonyl]vinyl]phenoxy]-1-methyleneethyl]        and about 1.5% of        methyl[3-[p-[2,2-bis(ethoxycarbonyl)vinyl)phenoxy)-propenyl) and        from 0.1 to 0.4% of (methylhydrogen]silylene]] (n≈60) (CAS No.        207 574-74-1, for example Parsol SLX),    -   2,2′-methylenebis(6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol)        (CAS No. 103 597-45-1, for example Tinosorb M),    -   2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)-1,3,5-triazine        (CAS No. 187 393-00-6, foe example Tinosorb S),    -   hexyl 2-(4-diethylamino-2-hydroxybenzoyl)benzoate (for example        Uvinul® UVA Plus).

The compounds listed should only be regarded as examples. It is ofcourse also possible to use other UV filters. These organic UV filters,like the compounds of the formula I, are generally incorporated into thecosmetic formulations according to the invention in an amount of from0.5 to 20% by weight, preferably in an amount of from 1 to 15% by weightand particularly preferably in amounts of from 2 to 8% by weight perindividual substance. In total, the cosmetic formulations according tothe invention usually comprise up to 40% by weight, preferably from 5 to25% by weight, of organic UV filters of this type.

Conceivable inorganic UV filters are those from the group consisting oftitanium dioxides, such as, for example, coated titanium dioxide (forexample Eusolex® T-2000, Eusolex® T-AQUA), zinc oxides (for exampleSachtotec®), iron oxides and also cerium oxides. These inorganic UVfilters are generally incorporated into the cosmetic formulationsaccording to the invention in an amount of from 0.5 to 20% by weight,preferably from 2 to 10% by weight.

If different inorganic or organic UV filters are employed, these can beused in virtually any desired ratios to one another. The ratios of theindividual substances to one another are usually in the range 1:10-10:1,preferably in the range 1:5-5:1 and particularly preferably in the range1:2-2:1. If UV-A filters are employed alongside UV-B filters, it isadvantageous for most applications for the proportion of UV-B filters topredominate and the ratio of UV-A filters:UV-B filters to be in therange from 1:1 to 1:10.

Preferred compounds having UV-filtering properties which are used in thecosmetic formulations according to the invention are3-(4′-methyl-benzylidene)-dl-camphor,1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)propane-1,3-dione,4-isopropyldibenzoylmethane, 2-hydroxy-4-methoxy-benzophenone, octylmethoxycinnamate, 3,3,5-trimethylcyclohexyl salicylate, 2-ethylhexyl4-(dimethylamino)benzoate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate andcoated titanium dioxide.

The cosmetic formulation according to the invention may also—apart fromthe compounds of the formulae Ia and Ib—comprise one or more amino acidsor pharmaceutically tolerated salts thereof. Preferred amino acids areselected from the group of compounds consisting of alanine, valine,leucine, isoleucine, proline, methionine, phenylalanine, tryptophan,glycine, serine, threonine, cysteine, tyrosine, asparagine, glutamine,lysine, arginine and histidine.

If the formulation according to the invention comprises amino acidswhich are different from the compounds of the formulae Ia and Ib, theproportion of these amino acids or pharmaceutically tolerated saltsthereof in the cosmetic formulation according to the invention ispreferably from 0.1 to 10% by weight, particularly preferably from 0.1to 8% by weight and especially preferably from 0.2 to 5% by weight,based on the formulation as a whole. The proportion of these amino acidsor pharmaceutically tolerated salts thereof in the cosmetic formulationaccording to the invention is very especially preferably from 0.2 to 2%by weight, based on the formulation as a whole.

If the formulation according to the invention comprises amino acidswhich are different from the compounds of the formulae Ia and Ib, the pHof the formulation is preferably less than 4.

The ingredients may be incorporated into the cosmetic formulationsaccording to the invention in a conventional manner. Formulations aresuitable for external application, for example as a cream, lotion orgel, or as a solution which can be sprayed onto the skin. It ispreferred here for the formulation to comprise at least one oil phaseand at least one water phase.

Application forms of the cosmetic formulations according to theinvention which may be mentioned are, for example: solutions, emulsions,PIT emulsions, suspensions, ointments, gels, creams, lotions, sprays andaerosols. Further application forms are, for example, sticks. Anydesired conventional vehicles, assistants and optionally further activeingredients may be added to the formulation.

Preferred assistants originate from the group consisting ofpreservatives, antioxidants, stabilisers, solubilisers, vitamins,colorants, odour improvers, film formers, thickeners and humectants.

Solutions and emulsions can comprise the conventional vehicles, such assolvents, solubilisers and emulsifiers, for example water, ethanol,isopropanol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzylbenzoate, propylene glycol, 1,3-butyl glycol, oils, in particularcottonseed oil, groundnut oil, maize oil, olive oil, castor oil andsesame oil, glycerol fatty acid esters, polyethylene glycols and fattyacid esters of sorbitan, or mixtures of these substances.

The emulsions may exist in various forms. Thus, they can be, forexample, an emulsion or microemulsion of the water-in-oil (W/O) type orof the oil-in-water (O/W) type, or a multiple emulsion, for example ofthe water-in-oil-in-water (W/O/W) type.

The cosmetic formulations according to the invention may also be in theform of emulsifier-free, disperse preparations. They can be, forexample, hydrodispersions or Pickering emulsions.

Suspensions may comprise conventional vehicles, such as liquid diluents,for example water, ethanol or propylene glycol, suspension media, forexample ethoxylated isostearyl alcohols, polyoxyethylene sorbitol estersand polyoxyethylene sorbitan esters, microcrystalline cellulose,aluminium metahydroxide, bentonite, agar-agar and tragacanth, ormixtures of these substances.

Pastes, ointments, gels and creams may comprise conventional vehicles,for example animal and vegetable fats, waxes, paraffins, starch,traga-canth, cellulose derivatives, polyethylene glycols, silicones,bentonites, silicic acid, talc and zinc oxide, or mixtures of thesesubstances.

Face and body oils may comprise the conventional vehicles, such assynthetic oils, such as fatty acid esters, fatty alcohols, siliconeoils, natural oils, such as vegetable oils and oily plant extracts,paraffin oils, lanolin oils, or mixtures of these substances.

Sprays may comprise the conventional propellants, for examplechlorofluorocarbons, propane/butane or dimethyl ether.

Further typical cosmetic application forms are, for example, make-up,such as, for example, emulsion make-up, and sun-protection, pre-sun andafter-sun preparations.

The cosmetic formulation according to the invention is particularlysuitable for protecting human skin against the harmful effects of the UVcomponents in sunlight and in addition it also offers protection againstageing processes in the skin and against oxidative stress, i.e. againstdamage caused by free radicals, as are produced, for example, by solarradiation, heat or other influences. In this connection, it is in thevarious administration forms usually used for this application. Forexample, it may, in particular, be in the form of a lotion or emulsion,such as in the form of a cream or milk (O/W, W/O, O/W/O, W/O/W), in theform of oily-alcoholic, oily-aqueous or aqueous-alcoholic gels orsolutions, in the form of solid sticks or may be formulated as anaerosol.

The formulation may comprise cosmetic adjuvants which are usually usedin this type of preparation, such as, for example, thickeners,softeners, moisturisers, surface-active agents, emulsifiers,preservatives, antifoams, perfumes, waxes, lanolin, propellants, dyesand/or pigments which colour the composition itself or the skin, andother ingredients usually used in cosmetics.

The dispersant or solubiliser used can be an oil, wax or other fattysubstance, a lower monoalcohol or lower polyol or mixtures thereof.Particularly preferred monoalcohols or polyols include ethanol,isopropanol, propylene glycol, glycerol and sorbitol.

A preferred embodiment of the invention is an emulsion in the form of acream or milk which comprises fatty alcohols, fatty acids, fatty acidesters, in particular triglycerides of fatty acids, lanolin, natural orsynthetic oils or waxes and emulsifiers in the presence of water.

Further preferred embodiments are oily lotions based on natural orsynthetic oils and waxes, lanolin, fatty acid esters, in particulartriglycerides of fatty acids, or oily-alcoholic lotions based on a loweralcohol, such as ethanol, or a glycol, such as propylene glycol, and/ora polyol, such as glycerol, and oils, waxes and fatty acid esters, suchas triglycerides of fatty acids.

The cosmetic formulation according to the invention may also be in theform of an alcoholic gel which comprises one or more lower alcohols orpolyols, such as ethanol, propylene glycol or glycerol, and a thickener,such as siliceous earth. The oily-alcoholic gels also comprise naturalor synthetic oil or wax.

The solid sticks consist of natural or synthetic waxes and oils, fattyalcohols, fatty acids, fatty acid esters, lanolin and other fattysubstances.

If a preparation is formulated as an aerosol, the conventionalpropellants, such as alkanes, fluoroalkanes and chlorofluoroalkanes, aregenerally used.

For protection of the skin against sunlight, a cosmetic formulationaccording to the invention is applied to the skin.

Even without further comments, it is assumed that a person skilled inthe art will be able to utilise the above description in its broadestscope. The preferred embodiments should therefore merely be regarded asdescriptive disclosure which is absolutely not to be regarded aslimiting in any way.

The complete disclosure content of all applications and publicationsmentioned above and below is incorporated into this application by wayof reference.

The cosmetic formulations according to the invention can be preparedwith the aid of techniques which are well known to the person skilled inthe art.

All compounds or components which can be used in the cosmeticformulations according to the invention are either known andcommercially available or can be obtained or prepared by methods whichare well known to the person skilled in the art and are described in theliterature (for example in standard works, such as Houben-Weyl, Methodender organischen Chemie [Methods of Organic Chemistry],Georg-Thieme-Verlag, Stuttgart).

The following examples are intended to illustrate the present invention.However, they should absolutely not be regarded as limiting.

The INCI names of the raw materials used are as follows:

Raw material INCI name Cetiol Oleyl Oleate DihydroxyacetoneDihydroxyacetone Dow Corning 3225 C Cyclomethicone, Dimethicone CopolyolEmulsifier E 2155 Steareth-10, Steareth-7, Stearyl Alcohol Imwitor 900Glyceryl Stearate Luvitol EHO Cetearyl Octanoate Methyl4-hydroxybenzoate Methylparaben Miglyol 812 N Caprylic/CapricTriglyceride Paracera M Microwax Propane-1,2-diol Propylene GlycolPropyl 4-hydroxybenzoate Propylparaben RonaCare ™ ectoin Ectoin TeginAcid H Glyceryl Stearate, Ceteth-20 Water, demineralised Aqua (Water)

EXAMPLES Example 1

Self-tanning lotion (O/W) % by wt. A Emulsifier E 2155 (1) 3.0 TeginAcid H (1) 3.0 Imwitor 900 (2) 3.0 Paracera M (3) 1.0 Cetiol (4) 8.5Luvitol EHO (5) 11.5 Miglyol 812 N (6) 8.5 Propyl 4-hydroxybenzoate (7)0.05 B Propane-1,2-diol (7) 4.0 Water, demineralised 42.2 Methyl4-hydroxybenzoate (7) 0.15 C Dihydroxyacetone (7) 5.0 RonaCare ™ ectoin(1) 0.1 Water, demineralised 10.0Preparation

Phase A is heated to 75° C. and phase B to 80° C. Phase B issubsequently added slowly to phase A with stirring and homogenised. Atabout 40° C., phase C is added and allowed to cool with stirring.

Sources of supply (1) Th. Goldschmidt AG (2) Huls AG (3) Paramelt (4)Cognis GmbH (5) BASF AG (6) Condea Chemie GmbH (7) Merck KGaA

Example 2

Self-tanning milk (W/O) % by wt. A Dow Corning 3225 C (2) 23.6 BDihydroxyacetone (1)  5.0 Propane-1,2-diol (1) 35.9 Preservatives q.s.RonaCare ™ ectoin (1)  1.0 Water, demineralised to 100Preparation

Phase B is dissolved and subsequently stirred into phase A.

The preservatives used are the following:

-   0.05% of propyl 4-hydroxybenzoate-   0.15% of methyl 4-hydroxybenzoate

Sources of supply (1) Merck KGaA (2) Dow Corning

1. A cosmetic composition comprising dihydroxyacetone, a topicalvehicle, and a compound of formula Ia or Ib, or a pharmaceuticallyacceptable salt of a compound of formula Ia or Ib

wherein R¹ is H or alkyl, R² is H, COOH, COO-alkyl or CO—NH—R⁵, R³ andR⁴ are each, independently of one another, H or OH, n is 1, 2 or 3,alkyl is an alkyl radical having 1 to 4 carbon atoms, and R⁵ is H,alkyl, an amino acid radical, a dipeptide radical or a tripeptideradical.
 2. A cosmetic composition according to claim 1, which contains0.1 to 15% by weight of dihydroxyacetone based on the formulation as awhole.
 3. A cosmetic composition according to claim 1, which contain0.001 to 50% by weight of a compound of formula Ia or Ib, or apharmaceutically acceptable salt of a compound of formula Ia or Ib basedon the formulation as a whole.
 4. A cosmetic composition according toclaim 1, wherein the compound of formula Ia or Ib is(S)-1,4,5,6-tetrahydro-2-methyl4-pyrimidinecarboxylic acid and(S,S)-1,4,5,6-tetrahydro-5-hydroxy-2-methyl-4-pyrimidinecarboxylic acid.5. A cosmetic composition according to claim 1, further comprising oneor more antioxidants.
 6. A cosmetic composition according to claim 1,further comprising one or more UV filters.
 7. A cosmetic compositionaccording to claim 1, which is a composition used for self-tanning, forday care or light-protection.
 8. A method for augmenting theUV-A-protective action of dihydroxyacetone comprising formulating acosmetic composition of claim 1 which comprise bringing into saidcosmetic dihydroxyacetone and a compound of formula Ia or Ib, or apharmaceutically acceptable salt of a compound of formula Ia or Ib.
 9. Acosmetic composition according to claim 1, which contains astereoisomeric form of a compound of formula Ia or Ib.
 10. A cosmeticcomposition according to claim 7, which is a composition used forlight-protection.